Merge bitcoin/bitcoin#34168: qa: Require --exclude for each excluded test

c5825d4b7f qa: Require `--exclude` for each excluded test (Hennadii Stepanov)

Pull request description:

  This PR allows a long `--exclude ...` argument in the `test/functional/test_runner.py` invocation to be split across multiple lines, with optional per-line explanatory comments. I found this useful for the CI scripts in https://github.com/hebasto/bitcoin-core-nightly.

ACKs for top commit:
  l0rinc:
    tested ACK c5825d4b7f
  maflcko:
    review ACK c5825d4b7f 🛄
  achow101:
    ACK c5825d4b7f
  rkrux:
    ACK c5825d4b7f

Tree-SHA512: bcf42848516197978b65df8a8bc68e036a62c9afc6158274eac74a325dc01991eb063a042f940c53ea15a7feb18d4bdfc45d8c71f0ef20c76140b12e07ba3ac5

.github/workflows/ci.yml

@@ -499,11 +499,13 @@ jobs:
 
       - name: Run functional tests
         env:
-          # TODO: Fix the excluded test and re-enable it.
-          # feature_unsupported_utxo_db.py fails on windows because of emojis in the test data directory
-          EXCLUDE: '--exclude wallet_multiwallet.py,feature_unsupported_utxo_db.py'
           TEST_RUNNER_EXTRA: ${{ github.event_name != 'pull_request' && '--extended' || '' }}
-        run: py -3 test/functional/test_runner.py --jobs $NUMBER_OF_PROCESSORS --ci --quiet --tmpdirprefix="$RUNNER_TEMP" --combinedlogslen=99999999 --timeout-factor=$TEST_RUNNER_TIMEOUT_FACTOR $EXCLUDE $TEST_RUNNER_EXTRA
+        run: |
+          py -3 test/functional/test_runner.py --jobs $NUMBER_OF_PROCESSORS --ci --quiet --tmpdirprefix="$RUNNER_TEMP" --combinedlogslen=99999999 --timeout-factor=$TEST_RUNNER_TIMEOUT_FACTOR $TEST_RUNNER_EXTRA \
+            `# feature_unsupported_utxo_db.py fails on Windows because of emojis in the test data directory.` \
+            --exclude feature_unsupported_utxo_db.py \
+            `# See https://github.com/bitcoin/bitcoin/issues/31409.` \
+            --exclude wallet_multiwallet.py
 
   ci-matrix:
     name: ${{ matrix.name }}